1. Public-facing risk checker
Designed to direct users toward appropriate care when mosquito exposure and neurological symptoms converge.
Complete the fields and calculate.
2. Clinician red-flag tool
A forcing function for adding West Nile neuroinvasive disease to the active differential.
Complete the fields and calculate.
3. Disambiguation flowchart: mosquito/tick-borne neuroinfectious syndromes
Acute febrile illness?
Fever, headache, myalgia, rash, vomiting, malaise.
Fever, headache, myalgia, rash, vomiting, malaise.
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Neurological involvement?
Meningitis, encephalitis, seizure, tremor, focal weakness, flaccid paralysis.
Meningitis, encephalitis, seizure, tremor, focal weakness, flaccid paralysis.
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Vector + geography
Mosquito vs tick, season, travel, wetlands, woods, local surveillance.
Mosquito vs tick, season, travel, wetlands, woods, local surveillance.
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Targeted differential
WNV, SLE, EEE, La Crosse, Jamestown Canyon, Powassan, Japanese encephalitis, dengue/chikungunya/Zika if travel.
WNV, SLE, EEE, La Crosse, Jamestown Canyon, Powassan, Japanese encephalitis, dengue/chikungunya/Zika if travel.
| Signal | Pushes reasoning toward | Comment |
|---|---|---|
| Older adult + summer mosquito exposure + encephalitis or flaccid weakness | West Nile virus | Dominant North American arboviral neuroinvasive disease pattern. |
| Child/adolescent + wooded exposure + seizures/encephalitis in eastern/upper midwestern US | La Crosse virus | Paediatric signal is important. |
| Severe encephalitis + high fatality concern + eastern/gulf-coast wetlands | Eastern equine encephalitis | Rare but high consequence; threshold for escalation should be low. |
| Encephalitis in western/southern US or regions with SLE activity | St Louis encephalitis | Clinically overlaps with WNV; lab/public-health context matters. |
| Adult neuroinvasive disease + deer/woodland mosquito ecology | Jamestown Canyon virus | Often under-recognised; consider in northern regions. |
| Tick exposure + meningoencephalitis, especially Great Lakes/northeast US/Canada | Powassan virus | Tick-borne; should separate from mosquito-borne branch. |
| Recent travel to Asia/western Pacific + rural pig/wading-bird ecology | Japanese encephalitis | Travel and vaccination history matter. |
4. Testing logic
Prompt: serum WNV IgM; add CSF WNV IgM when neurological symptoms are present.
If testing occurs very early, a negative IgM result should not automatically close the diagnosis if clinical suspicion remains. Repeat or confirmatory testing may be needed depending on timing and flavivirus cross-reactivity.
5. Cognitive-bias guardrail
Premature closureAvailability biasAnchoring on influenzaBase-rate neglectGeographic unfamiliarity
Bias warning: neurological features move this beyond a routine viral syndrome.
6. Decision output
Product principle: the tool does not diagnose WNV. It raises a rare, severe, seasonally plausible diagnosis into the active differential.
Reference architecture
| Layer | Inputs | Output |
|---|---|---|
| Exposure prior | Region, date, mosquito season, weather, mosquito pools, bird/equine signals, travel | Estimated exposure plausibility |
| Clinical syndrome | Fever, headache, rash, GI symptoms, neurological signs | Febrile / meningitic / encephalitic / paralytic phenotype |
| Vulnerability | Age, immune status, diabetes, hypertension, cardiovascular disease | Severity modifier |
| Diagnostic reasoning | Syndrome + exposure + local surveillance + differential diagnosis | Red-flag tier and testing prompt |
| Bias layer | Competing diagnosis, failure to consider vector disease, early negative test | Unfamiliarity and premature-closure warning |